Most online systems will be about 15 to 20 years old.
Not the shiny bit you see when you use them. But the backend that does the grunt work.
And I will guarantee that most of the expertise needed to fix any problems there is in very short supply.
The reason these things take so long to fix isn't technical. It's administrative as each layer of management your have to rise through to get to the top is desperately ensuring that it's not their "efficiencies" that are blamed.
Will nobody think of the shareholders ?